Quick Dips

Buzz of Excitement

The business of bumble-bees has taken Master of Applied Science student Marie Schaffer as far afield as Norway in her studies of just how efficient bumble-bees are in pollinating field crops and over what distances their usefulness can be relied on.

Schaffer, studying at Lincoln University, has been conducting field work on the Canterbury Plains looking at the role of bumble-bees in the pollination of lucerne. The key questions here are how far from their nests bumble-bees forage in lucerne and how efficient they are as lucerne pollinators.

"If farmers are to rely on bumble-bees to pollinate their lucerne, it's important to know how far the bees can travel from their nests -- you don't want a situation in which only the fringes of paddocks of lucerne are pollinated and the more distant centres left cold," says Schaffer's supervisor, Dr Steve Wratten, of the university's Department of Entomology and Animal Ecology.

In order to track the flight paths of the bumble-bees in a sample paddock of lucerne, Schaffer put a number of artificial nests in place nearby and rigged up a mechanism by which the bees received a dusting of a harmless fluorescent powder as they emerged from the nests on foraging flights. She then patrolled up and down the paddock recording and plotting the sightings of particular coloured bees.

From the data she collected Schaffer has produced a spatial representation of the coverage of the paddock by particular bees from particular nests. A considerable overlap is evident in the territories various bees covered, and while the paddock studied was an experimental one only 15 metres square, the feeling is that in any extrapolation to a larger plot, unpollinated spots would occur.

Throughout New Zealand bumble-bees are currently on the road to becoming big business. One company, Zonda Resources, is a national supplier of bumble-bee hives to greenhouses, particularly for pollinating tomatoes, melons and other fruits. Honey bees will not work in the confined spaces of greenhouses but bumble-bees have no such greenhouse claustrophobia. Also, unlike honey bees they can use their buzz to vibrate a flower -- an important attribute as some flowers, particularly members of the family to which tomatoes belong, need specific vibrations to release their pollen.

In recent years bumble-bees have emerged as highly successful greenhouse pollinators. In relation to tomatoes, research in Britain shows bumble-bee pollination, as opposed to artificial methods, can lead to an about 20% increase in yield and an improvement in size and shape.